Seeds are one of the most important tradable assets in agriculture. Seeds are of such a small volume, that they can be easily stored and transported; yet they represent an enormous value for the grower since they can develop into mature plants by simply growing them under the appropriate conditions. However, since growing of plants (crops) from seeds also needs to be done in a cost-efficient fashion, the quality of the seeds and the biological process of sprouting should be as optimal as possible. One of the factors that needs to be controlled is the timing of germination of the seed, since this determines the timing of harvest. For production of crops, it is essential that the growth of all plants occurs simultaneously, to provide for a uniform product and to economize the growing of the plants and the harvesting of the crops. One of the ways to achieve this, is to prime the seeds.
Priming mainly concerns pre-treatment of the seeds to provide water in a controlled manner. This will initiate early stages of germination, but does not permit radicle protrusion. After priming the seeds are dried again. Later on, after sowing and exposure to water these primed seeds germinate faster, and seedling emergence is synchronised. Benefits of priming are a higher germination percentage (called ‘germination capacity”), while seeds also may germinate faster (called “germination energy”). In addition, the uniformity of seedling emergence is enhanced. Different priming methods are known, such as osmo-priming (using liquid carriers of water), matrix priming (using solid water carriers) or hydro priming (using pure water).
Use of electric or electromagnetic fields to influence the growing characteristics of plants has occasionally been investigated since the first days of the electric age. Although many, often anecdotic and fragmentary experimental data are available, the results of those experiments are not univocal. One of the reasons is that there are many experimental parameters which can be varied, such as the type of field (magnetic, electromagnetic, electrostatic, electric, AC or DC, and even plasma fields), the strength of the field (or the distance to the source of the field), the frequency (in case of AC fields), the duration of the treatment, the type of plant or plant part that is treated, influence of other environmental conditions, and the like. In general, it can be said that many investigators have found beneficial effects on growth rates, yield size and quality by applying these kind of fields, although also no effects or even deteriorating effects have been reported. Also, in some field experiments, the beneficial effect can have been established by the fact that the applied fields were harmful for pathogens of the plants and that thus the plants could grow unhindered by disease (such as presumed in WO 02/39786).
Recently, some more serious investigations into the role of these kinds of energy fields in agriculture have been published. Ark, P. A. and Parry, W. (Quart. Rev. Biol., 1940, 15(2):172-191; see also U.S. Pat. No. 2,308,204) focused on the use of high-frequency electrostatic fields in agriculture for eradication of plant pathogens, such as fungi and nematodes. A similar application has been recently described by Cwiklinski, C. and von Hörsten, D. (ASAE Annual Meeting, 2001 paper #01671), Nelson, S. O. et al., (Trans. ASAE, 2002, 45(6):1937-1942), and by Wayland, J. R. (U.S. Pat. No. 5,060,414).
UHF electromagnetic fields have been reported to be phytotoxic (Davis, F. S. et al., 1973, Nature 242:291-292). However, also beneficial effects on germination and growth have been reported recently by Celestino C. et al. with a 50 Hz electromagnetic field on Quercus ruber seeds (Electro- and Magnetobiology, 2000, 19:115-120), by Moon, J-D. and Chung H-S. with various AC electric and magnetic fields on seeds of tomato (J. Electrostatics, 2000, 48(2):103-114), with a pulsed electromagnetic system on sprouted seeds and beans in a press release of EarthPulse Technologies LLC (Bengalore, India, Apr. 11, 2006), by Kalinin, L. G. et al. with a low-frequency pulse electromagnetic field on various kinds of seeds (Biofizika, 2005, 50(2), 361-366), and by Lynikiene, S et al. with a corona discharge field on carrot, radish, beet and barley seeds (Int. Agrophysics, 2006, 20:195-200). U.S. Pat. No. 5,740,627 describes the use of ‘avalanches of ion-electrons’ for treating seeds, especially tomato seeds, which causes enhanced growth characteristics of plants emerging from those seeds.
WO 02/39786 describes application of radiofrequency fields to biologic tissue and food in order to provide thermal energy by which micro-organisms are killed. This document also shows the treatment of plants and plant parts and shows that these plant demonstrate improved growing characteristics due to the absence of (pathogenic) micro-organisms.
One of the main disadvantages of the above described methods using electrical fields is that most of them use high to very high voltage electric fields, which of course implies a danger for the operators performing the treatment and which can detoriate the biological material that is treated. Especially in the cases where heat is generated by applying the electrical field the implicit damaging of cells jeopardizes a widespread use of these kinds of fields.